.wrap{
    div{
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0,0,0,.3);
    }
    img{
        position: fixed;
        top: 50%;
        left: 50%;
        width: .75rem;
        transform: translate(-50%, -50%);
    }
}